Ferrino Posted December 6, 2004 Share Posted December 6, 2004 On the lookout for a cheap & light alternative to my heavy Spitfire front brakes, I was interested in the 2-pot ali brakes by Hi-Spec (Ultralites) see here. I spoke to Hi-Spec and apparently the lug-mounts will fit straight onto the Caterham upright, therefore not needing an adapter bracket. They also say that it will fit the standard Triumph disc (but I don't have any dimensions to hand to check). At £180+VAT they seem like a good buy and I think they would be more than adequate for a BEC? What do you think? Lobbying Caterham for a new badge.... Edited by - Ferrino on 6 Dec 2004 12:41:34 Link to comment Share on other sites More sharing options...
Area Representative Crudders Posted December 6, 2004 Area Representative Share Posted December 6, 2004 I'm not really qualified to answer your question Ferrino but I would have thought they'd be adequate in pure braking power terms given the minimal mass they'd be asked to pull up in a BEC. I also like the look of them and would be interested in acquiring some, subject to a bit of positive feedback here from anyone who has used them. Bulk Buy anyone ? Richard []=*(#7#)*=[] b-r-a-a-a-a-r-p! Visit the North Kent Area here Link to comment Share on other sites More sharing options...
timbo Posted December 6, 2004 Share Posted December 6, 2004 Well, as long as you don't expect to get any good customer service for £180 you'll be alright. Emerald Isle's 1st SV 148lbft @ 6091rpm and 182bhp @ 6690rpm Link to comment Share on other sites More sharing options...
Joe 90 Posted December 6, 2004 Share Posted December 6, 2004 Braking power is predominantly about the heat rejection capacity of the disks, so it should be at least as good as a standard setup. SEP field working, not spotted in 103,000 miles. Some photos on webshots, updated 21 Sept Link to comment Share on other sites More sharing options...
xflow7 Posted December 6, 2004 Share Posted December 6, 2004 Have you compared piston areas with the current calipers to ensure the brake balance doesn't get drastically altered? Dave Link to comment Share on other sites More sharing options...
barry.h Posted December 6, 2004 Share Posted December 6, 2004 I use the 2 pot Alcon (James Whiting) on my Blackbird and they do a good job - and they weigh a lot less than 4 pot. Barry Link to comment Share on other sites More sharing options...
Ferrino Posted December 6, 2004 Author Share Posted December 6, 2004 Have you compared piston areas with the current calipers to ensure the brake balance doesn't get drastically altered?Haven't had a chance to check my Triumph calliper pot dimensions, but I'm guessing that if people go from 2-pot -> 4-pot without uprating the rears or adding bias-adjustment to compensate then 2-pot -> 2-pot shouldn't be troublesome [Flame-suit on] Lobbying Caterham for a new badge.... Link to comment Share on other sites More sharing options...
Normans_Ghost Posted December 6, 2004 Share Posted December 6, 2004 Wilwood seem Ok. Not sure if the 2 pot is a straight fit. My book says 69.50 each for unpolished, 99.50 for the shiny ones. ring 01795 531871 and ask. I've read a story on the net about Hi Spec, Sounds like Basil Fawlty has gone into the brake business. Not sure if Manuel is still with him or if does auto as well. Norman Verona, 1989 BDR 220bhp, Mem No 2166, the full story here Link to comment Share on other sites More sharing options...
Area Representative Crudders Posted December 6, 2004 Area Representative Share Posted December 6, 2004 Looks like I was being a tad optimistic on the positive feedback front then Norm If Wilwood can be had for that sort of money i'll go for them - I thought they were dearer than that. Cheers. Richard []=*(#7#)*=[] b-r-a-a-a-a-r-p! Visit the North Kent Area here Link to comment Share on other sites More sharing options...
Luke Beaumont Posted December 6, 2004 Share Posted December 6, 2004 I have in my notes that the Triumph calipers use 48mm pistons, so the Hispecs on 34.6mm would have nearly half the piston area. I believe this would give the front hydraulic circuit less force amplification and a harder pedal (he said, still trying to fully understand hydraulics). Link to comment Share on other sites More sharing options...
xflow7 Posted December 6, 2004 Share Posted December 6, 2004 Haven't had a chance to check my Triumph calliper pot dimensions, but I'm guessing that if people go from 2-pot -> 4-pot without uprating the rears or adding bias-adjustment to compensate then 2-pot -> 2-pot shouldn't be troublesome [Flame-suit on] Don't worry; flame-thrower securely holstered. 😬 You may well be right. It's something that I've always wondered that about 4-pot conversions, too. It wouldn't surprise me if the popular 4-pot conversions don't actually increase piston area all that much, but rather just use more, smaller pistons to achieve a more advantageous load distribution on the pad. It's also possible that, in general, people who fit 4-pots have also already fitted stickier tires, etc that enable higher peak deceleration more load transfer ability to use more forward bias. Anyhow, as I say, just a question that popped into my head. Dave Link to comment Share on other sites More sharing options...
steve_m Posted December 6, 2004 Share Posted December 6, 2004 I've got Hi-Spec 4 pot ultralites on my car (475 Kg) and they are fantastic. 800g each. The 2 pots might be slightly lighter. I've always found Hi-Spec service to be good, on the whole I'd buy them again, no problem. It's funny how all the positive feedback gets put to one side and people repeat the negative . . . suppose that's the way we are In fact I'm waiting for the Sierra replacement rear callipers - as soon as they're available I'll be ordering them. Link to comment Share on other sites More sharing options...
Ferrino Posted December 6, 2004 Author Share Posted December 6, 2004 They were definitely very helpful over the phone and were happy for me to bring along an upright/disc assembly to double-check sizes/clearance. They actually list the weight of the 2-pots as 800g and the 4-pots as 850g - I believe they use the same shell. 4-pots are only £17 extra (per calliper) as well. As I am redoing the brake lines anyway, would it be better to plumb in a simple bias valve and get the 4-pots? Are you using standard discs Steve? Edited by - Ferrino on 6 Dec 2004 16:36:14 Link to comment Share on other sites More sharing options...
Joe 90 Posted December 6, 2004 Share Posted December 6, 2004 If the pistons are smaller it will reduce front brake effort and give a softer pedal . You probably don't want either of those ❗ The standard Triumph calipers have pretty large pistons, which meant that I could find a Wilwood 4 pot caliper with almost exactly the same piston area as the 2 pot Triumph. SEP field working, not spotted in 103,000 miles. Some photos on webshots, updated 21 Sept Link to comment Share on other sites More sharing options...
Luke Beaumont Posted December 6, 2004 Share Posted December 6, 2004 I'll admit that I'm not hugely sure of my ground here, but having tried to understand this for the VW rear caliper musings, are you sure about that Oliver? A smaller caliper area means less pedal movement for a given movement at the caliper, and as a result more pressure needed at the pedal to give an equivalent force onto the disc. Link to comment Share on other sites More sharing options...
Dan J Posted December 6, 2004 Share Posted December 6, 2004 Hi-spec do not not have the best rep for customer service (just do a web search), however they do make very nice callipers and have an excellent agent in Martin Bell at: www.thekitcarworkshop.co.uk No connection etc, just a happy customer. If you want Hispecs go through Martin - it's the same price BUT he goes out of his way to ensure that everything is spot on and you're happy. Dan Link to comment Share on other sites More sharing options...
Joe 90 Posted December 6, 2004 Share Posted December 6, 2004 Braking effort is set by force, which is pressure times area. The same pressure (generated by the same pedal effort on the same master cylinder piston) will generate less pad force because the caliper piston area is smaller. The rears are unaffected, so there is more rear bias. Thinking about it a bit more, it would make the pedal a bit firmer, as you need more hydraulic pressure to give the same pad force. SEP field working, not spotted in 103,000 miles. Some photos on webshots, updated 21 Sept Link to comment Share on other sites More sharing options...
Ferrino Posted December 6, 2004 Author Share Posted December 6, 2004 OK, I have tried to compare the piston area between a single Triumph piston vs. a single Hi-Spec piston: Triumph piston diameter = 48mm = area of 18.1cm^2 Hi-Spec piston diameter = 34.6mm = area of 9.4 cm^2 Therefore, the 2-pot Hi-Spec callipers will have 52% of the Triumph area, and the 4-pot Hi-Spec callipers will have 104% of the Triumph area. Assuming my calcs are correct, should I take these results to mean that the 4-pots are the best choice to preserve the current bias (assuming all else to be equal, which they are not with the resultant weight loss of the BEC)? Lobbying Caterham for a new badge.... Link to comment Share on other sites More sharing options...
deanteam Posted December 7, 2004 Share Posted December 7, 2004 Not an expert but does the piston area relate to the effort/feel so if you remain with same piston area the brake should feel similar, there are probably some geometric factors related to multi cylinders but have not calculated it!. However isn't the idea of 4-pots to get greater pad area, and as has been said spread the load more effectively? The question is then if you go to 4-pots do you get greater pad area? If so then would this increase braking? I have changed the orginal calipers for the Alcon 2-pot set, the braking is similar as I have retained the same pads. Link to comment Share on other sites More sharing options...
Joe 90 Posted December 7, 2004 Share Posted December 7, 2004 I don't know of any 4-pot adjustments to be made, and I used a straight area calculation when chosing my Wilwood 4 pots. A big advantage of the 4 pots is that they spread the force more evenly over the typical rectangular(ish) pad, whilst the 2 pot will load the centre of the pad more. I think it's crucial to remember that upsetting the front to rear balance can be dangerous. Pedal effort and feel has a lot more lattitude, and can be changed to suit driver preference. SEP field working, not spotted in 103,000 miles. Some photos on webshots, updated 21 Sept Link to comment Share on other sites More sharing options...
Mike Biddle Posted December 7, 2004 Share Posted December 7, 2004 I have the high spec 4 pots but with 280mm solid discs with aluminium bells, and they fit under 13' rims. 1KG lighter than the standard set up, monster braking power, and more controlable due to the big disc diameter. I found Hi spec to be very helpfull, and they gave me an excellent service. Link to comment Share on other sites More sharing options...
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